During cardiac arrest, the heart ceases to pump blood. Subsequently, there is no circulation, and the brain fails to receive freshly oxygenated blood. Without a steady supply of oxygenated blood, the brain will cease to function.
Current resuscitation techniques for cardiac arrest result in low patient survival rates. In hospitals and clinics with advanced cardiopulmonary resuscitation (CPR) and life support systems, the survival rate is normally around 14%. Outside of hospital settings, the survival rate is about 5%.
Among cardiac arrest victims overall, less than 10% survive neurologically intact and without significant brain damage. The other approximately 90% either die or sustain some neurologic injury from ischemia, (i.e., lack of blood flow to the brain), or anoxia (i.e., lack of oxygen to the brain). Such frequency of neurologic injury occurs because after cardiac arrest, basic cardiopulmonary resuscitation and advanced life support techniques, such as CPR, closed heart cardiac chest massage, and electroshock treatments, typically require fifteen to twenty minutes to regain circulation from a failed heart. With conventional resuscitation methods, irreversible neurologic damage begins soon after circulation stops. Therefore, it is imperative to restart the heat as soon as possible.